The invention relates to a flange for compensator couplings or pipes, consisting of a circular ring provided with apertures for the assembly bolts.
Flanges are essential components for assembly of pipes in industrial piping. This assembly consists of connecting the flanges in pairs to the ends of the pipes, and compressing a gasket between the flanges. This assembly is obtained by means of bolts which pass through the apertures of the flanges.
The term "flange(s)" as used above and throughout the description includes both the actual flanges, and the mating flanges, a term which sometimes designates lapped flanges.
More specifically, according to FIGS. 1 and 2, the pipes 1 are in general provided at one end with a welded flange 2, and the other end can also contain a welded flange or a free flange 3 disposed behind a flat collar 4 welded to the end of the pipe.
According to a variant, the flange 3 is disposed behind a turned-up collar 4', provided directly at the end of the pipe 1 or welded to the latter.
The flanges 2, 3 are provided with apertures 5 for passage of bolts, not shown.
There are also cases where two pipes 1, 10, which are provided at their corresponding ends with a flange 2, 12, are assembled by means of a compensator coupling 11 (FIG. 3). The actual coupling 11 consists of a multi-layer metal carcass with reinforcement of the flat sealing bead 15, provided with an inner lining 16 and an outer lining 17, the linings being made of rubber or a plastics material which is resistant to the fluid which flows in the pipes. At the ends, there are two mating flanges 18, which are factory-mounted on the coupling 11.
The coupling 11 is attached to the flanges 12, 13 of the pipes by means of mating flanges 18, and at the same time the edges 19 of the coupling 11 constitute the gasket. Assembly is by means of the bolts 32.
These compensator couplings permit absorbtion of faults of alignment (parallax or inclination) or expansion of the pipes 1, 10, or hammer blows They prevent or reduce transmission of vibrations.
The flanges or mating flanges, in particular those of compensator couplings, are currently made by machining of flame-cut parts, by forging, or from grey cast iron. However this last solution is only suitable for flanges which are not destined to be welded, since cast iron is involved. These cast iron flanges also have the disadvantage that they are heavy and fragile.
The actual flanges are welded to the pipes, whereas the mating flanges are fitted on the end of the pipes. The flanges of the compensator couplings are factory-mounted on the resilient couplings, and are supplied assembled to the user.
The weight of the flanges is an important factor, since the price of a flange depends directly on its weight, as all the operations carried out on the flanges (surface treatment, transport, etc.) are invoiced by weight.
The dimensional tolerances and accuracy of the flanges currently manufactured is often unsatisfactory, since for reasons of labour cost, the flanges are mainly manufactured in countries with a low labour cost, on poorly developed machines; the dimensions of all the parts have to be checked, and if necessary, adjustments must be made by machining.
This work is lengthy and costly. There are also the problems of long supply lead times, and high stock control cost.
In greater detail, there are a given number of prior art documents which describe flanges.
For example document U.S. Pat. No. 2,528,343 describes a flanges which is provided with trapezoidal openings distributed in a fan-shape, in order to permit absorbtion of slight faults of correspondence of the openings of the other flange.
Another document U.S. Pat. No. 4,372,587 describes a flange composed of two halves which have ends on both sides in lugs. The two halves are connected by bolts which pass through the two arms, in order to clamp and fasten this flange by means of teeth onto the pipe. After this assembly, the flange is connected to the flange of the other pipe.
This flange which is composed of two parts relates to a very specific requirement, i.e. that of fastening a flange to the end of a pipe by means of a relatively large fastening surface thickness of the flange must be increased locally as compared to a conventional flange.
To summarise, there are different shapes of flanges, but in no case does the prior art refer to transmission and distribution of forces in a flange, associated with weight reduction of the latter.